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sunvdc.c

/* sunvdc.c: Sun LDOM Virtual Disk Client.
 *
 * Copyright (C) 2007 David S. Miller <davem@davemloft.net>
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/blkdev.h>
#include <linux/hdreg.h>
#include <linux/genhd.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/scatterlist.h>

#include <asm/vio.h>
#include <asm/ldc.h>

#define DRV_MODULE_NAME       "sunvdc"
#define PFX DRV_MODULE_NAME   ": "
#define DRV_MODULE_VERSION    "1.0"
#define DRV_MODULE_RELDATE    "June 25, 2007"

static char version[] __devinitdata =
      DRV_MODULE_NAME ".c:v" DRV_MODULE_VERSION " (" DRV_MODULE_RELDATE ")\n";
MODULE_AUTHOR("David S. Miller (davem@davemloft.net)");
MODULE_DESCRIPTION("Sun LDOM virtual disk client driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_MODULE_VERSION);

#define VDC_TX_RING_SIZE      256

#define WAITING_FOR_LINK_UP   0x01
#define WAITING_FOR_TX_SPACE  0x02
#define WAITING_FOR_GEN_CMD   0x04
#define WAITING_FOR_ANY       -1

struct vdc_req_entry {
      struct request          *req;
};

struct vdc_port {
      struct vio_driver_state vio;

      struct gendisk          *disk;

      struct vdc_completion   *cmp;

      u64               req_id;
      u64               seq;
      struct vdc_req_entry    rq_arr[VDC_TX_RING_SIZE];

      unsigned long           ring_cookies;

      u64               max_xfer_size;
      u32               vdisk_block_size;

      /* The server fills these in for us in the disk attribute
       * ACK packet.
       */
      u64               operations;
      u32               vdisk_size;
      u8                vdisk_type;

      char              disk_name[32];

      struct vio_disk_geom    geom;
      struct vio_disk_vtoc    label;
};

static inline struct vdc_port *to_vdc_port(struct vio_driver_state *vio)
{
      return container_of(vio, struct vdc_port, vio);
}

/* Ordered from largest major to lowest */
static struct vio_version vdc_versions[] = {
      { .major = 1, .minor = 0 },
};

#define VDCBLK_NAME     "vdisk"
static int vdc_major;
#define PARTITION_SHIFT 3

static inline u32 vdc_tx_dring_avail(struct vio_dring_state *dr)
{
      return vio_dring_avail(dr, VDC_TX_RING_SIZE);
}

static int vdc_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
      struct gendisk *disk = bdev->bd_disk;
      struct vdc_port *port = disk->private_data;

      geo->heads = (u8) port->geom.num_hd;
      geo->sectors = (u8) port->geom.num_sec;
      geo->cylinders = port->geom.num_cyl;

      return 0;
}

static struct block_device_operations vdc_fops = {
      .owner            = THIS_MODULE,
      .getgeo           = vdc_getgeo,
};

static void vdc_finish(struct vio_driver_state *vio, int err, int waiting_for)
{
      if (vio->cmp &&
          (waiting_for == -1 ||
           vio->cmp->waiting_for == waiting_for)) {
            vio->cmp->err = err;
            complete(&vio->cmp->com);
            vio->cmp = NULL;
      }
}

static void vdc_handshake_complete(struct vio_driver_state *vio)
{
      vdc_finish(vio, 0, WAITING_FOR_LINK_UP);
}

static int vdc_handle_unknown(struct vdc_port *port, void *arg)
{
      struct vio_msg_tag *pkt = arg;

      printk(KERN_ERR PFX "Received unknown msg [%02x:%02x:%04x:%08x]\n",
             pkt->type, pkt->stype, pkt->stype_env, pkt->sid);
      printk(KERN_ERR PFX "Resetting connection.\n");

      ldc_disconnect(port->vio.lp);

      return -ECONNRESET;
}

static int vdc_send_attr(struct vio_driver_state *vio)
{
      struct vdc_port *port = to_vdc_port(vio);
      struct vio_disk_attr_info pkt;

      memset(&pkt, 0, sizeof(pkt));

      pkt.tag.type = VIO_TYPE_CTRL;
      pkt.tag.stype = VIO_SUBTYPE_INFO;
      pkt.tag.stype_env = VIO_ATTR_INFO;
      pkt.tag.sid = vio_send_sid(vio);

      pkt.xfer_mode = VIO_DRING_MODE;
      pkt.vdisk_block_size = port->vdisk_block_size;
      pkt.max_xfer_size = port->max_xfer_size;

      viodbg(HS, "SEND ATTR xfer_mode[0x%x] blksz[%u] max_xfer[%lu]\n",
             pkt.xfer_mode, pkt.vdisk_block_size, pkt.max_xfer_size);

      return vio_ldc_send(&port->vio, &pkt, sizeof(pkt));
}

static int vdc_handle_attr(struct vio_driver_state *vio, void *arg)
{
      struct vdc_port *port = to_vdc_port(vio);
      struct vio_disk_attr_info *pkt = arg;

      viodbg(HS, "GOT ATTR stype[0x%x] ops[%lx] disk_size[%lu] disk_type[%x] "
             "xfer_mode[0x%x] blksz[%u] max_xfer[%lu]\n",
             pkt->tag.stype, pkt->operations,
             pkt->vdisk_size, pkt->vdisk_type,
             pkt->xfer_mode, pkt->vdisk_block_size,
             pkt->max_xfer_size);

      if (pkt->tag.stype == VIO_SUBTYPE_ACK) {
            switch (pkt->vdisk_type) {
            case VD_DISK_TYPE_DISK:
            case VD_DISK_TYPE_SLICE:
                  break;

            default:
                  printk(KERN_ERR PFX "%s: Bogus vdisk_type 0x%x\n",
                         vio->name, pkt->vdisk_type);
                  return -ECONNRESET;
            }

            if (pkt->vdisk_block_size > port->vdisk_block_size) {
                  printk(KERN_ERR PFX "%s: BLOCK size increased "
                         "%u --> %u\n",
                         vio->name,
                         port->vdisk_block_size, pkt->vdisk_block_size);
                  return -ECONNRESET;
            }

            port->operations = pkt->operations;
            port->vdisk_size = pkt->vdisk_size;
            port->vdisk_type = pkt->vdisk_type;
            if (pkt->max_xfer_size < port->max_xfer_size)
                  port->max_xfer_size = pkt->max_xfer_size;
            port->vdisk_block_size = pkt->vdisk_block_size;
            return 0;
      } else {
            printk(KERN_ERR PFX "%s: Attribute NACK\n", vio->name);

            return -ECONNRESET;
      }
}

static void vdc_end_special(struct vdc_port *port, struct vio_disk_desc *desc)
{
      int err = desc->status;

      vdc_finish(&port->vio, -err, WAITING_FOR_GEN_CMD);
}

static void vdc_end_request(struct request *req, int uptodate, int num_sectors)
{
      if (end_that_request_first(req, uptodate, num_sectors))
            return;
      add_disk_randomness(req->rq_disk);
      end_that_request_last(req, uptodate);
}

static void vdc_end_one(struct vdc_port *port, struct vio_dring_state *dr,
                  unsigned int index)
{
      struct vio_disk_desc *desc = vio_dring_entry(dr, index);
      struct vdc_req_entry *rqe = &port->rq_arr[index];
      struct request *req;

      if (unlikely(desc->hdr.state != VIO_DESC_DONE))
            return;

      ldc_unmap(port->vio.lp, desc->cookies, desc->ncookies);
      desc->hdr.state = VIO_DESC_FREE;
      dr->cons = (index + 1) & (VDC_TX_RING_SIZE - 1);

      req = rqe->req;
      if (req == NULL) {
            vdc_end_special(port, desc);
            return;
      }

      rqe->req = NULL;

      vdc_end_request(req, !desc->status, desc->size >> 9);

      if (blk_queue_stopped(port->disk->queue))
            blk_start_queue(port->disk->queue);
}

static int vdc_ack(struct vdc_port *port, void *msgbuf)
{
      struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
      struct vio_dring_data *pkt = msgbuf;

      if (unlikely(pkt->dring_ident != dr->ident ||
                 pkt->start_idx != pkt->end_idx ||
                 pkt->start_idx >= VDC_TX_RING_SIZE))
            return 0;

      vdc_end_one(port, dr, pkt->start_idx);

      return 0;
}

static int vdc_nack(struct vdc_port *port, void *msgbuf)
{
      /* XXX Implement me XXX */
      return 0;
}

static void vdc_event(void *arg, int event)
{
      struct vdc_port *port = arg;
      struct vio_driver_state *vio = &port->vio;
      unsigned long flags;
      int err;

      spin_lock_irqsave(&vio->lock, flags);

      if (unlikely(event == LDC_EVENT_RESET ||
                 event == LDC_EVENT_UP)) {
            vio_link_state_change(vio, event);
            spin_unlock_irqrestore(&vio->lock, flags);
            return;
      }

      if (unlikely(event != LDC_EVENT_DATA_READY)) {
            printk(KERN_WARNING PFX "Unexpected LDC event %d\n", event);
            spin_unlock_irqrestore(&vio->lock, flags);
            return;
      }

      err = 0;
      while (1) {
            union {
                  struct vio_msg_tag tag;
                  u64 raw[8];
            } msgbuf;

            err = ldc_read(vio->lp, &msgbuf, sizeof(msgbuf));
            if (unlikely(err < 0)) {
                  if (err == -ECONNRESET)
                        vio_conn_reset(vio);
                  break;
            }
            if (err == 0)
                  break;
            viodbg(DATA, "TAG [%02x:%02x:%04x:%08x]\n",
                   msgbuf.tag.type,
                   msgbuf.tag.stype,
                   msgbuf.tag.stype_env,
                   msgbuf.tag.sid);
            err = vio_validate_sid(vio, &msgbuf.tag);
            if (err < 0)
                  break;

            if (likely(msgbuf.tag.type == VIO_TYPE_DATA)) {
                  if (msgbuf.tag.stype == VIO_SUBTYPE_ACK)
                        err = vdc_ack(port, &msgbuf);
                  else if (msgbuf.tag.stype == VIO_SUBTYPE_NACK)
                        err = vdc_nack(port, &msgbuf);
                  else
                        err = vdc_handle_unknown(port, &msgbuf);
            } else if (msgbuf.tag.type == VIO_TYPE_CTRL) {
                  err = vio_control_pkt_engine(vio, &msgbuf);
            } else {
                  err = vdc_handle_unknown(port, &msgbuf);
            }
            if (err < 0)
                  break;
      }
      if (err < 0)
            vdc_finish(&port->vio, err, WAITING_FOR_ANY);
      spin_unlock_irqrestore(&vio->lock, flags);
}

static int __vdc_tx_trigger(struct vdc_port *port)
{
      struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
      struct vio_dring_data hdr = {
            .tag = {
                  .type       = VIO_TYPE_DATA,
                  .stype            = VIO_SUBTYPE_INFO,
                  .stype_env  = VIO_DRING_DATA,
                  .sid        = vio_send_sid(&port->vio),
            },
            .dring_ident            = dr->ident,
            .start_idx        = dr->prod,
            .end_idx          = dr->prod,
      };
      int err, delay;

      hdr.seq = dr->snd_nxt;
      delay = 1;
      do {
            err = vio_ldc_send(&port->vio, &hdr, sizeof(hdr));
            if (err > 0) {
                  dr->snd_nxt++;
                  break;
            }
            udelay(delay);
            if ((delay <<= 1) > 128)
                  delay = 128;
      } while (err == -EAGAIN);

      return err;
}

static int __send_request(struct request *req)
{
      struct vdc_port *port = req->rq_disk->private_data;
      struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
      struct scatterlist sg[port->ring_cookies];
      struct vdc_req_entry *rqe;
      struct vio_disk_desc *desc;
      unsigned int map_perm;
      int nsg, err, i;
      u64 len;
      u8 op;

      map_perm = LDC_MAP_SHADOW | LDC_MAP_DIRECT | LDC_MAP_IO;

      if (rq_data_dir(req) == READ) {
            map_perm |= LDC_MAP_W;
            op = VD_OP_BREAD;
      } else {
            map_perm |= LDC_MAP_R;
            op = VD_OP_BWRITE;
      }

      sg_init_table(sg, port->ring_cookies);
      nsg = blk_rq_map_sg(req->q, req, sg);

      len = 0;
      for (i = 0; i < nsg; i++)
            len += sg[i].length;

      if (unlikely(vdc_tx_dring_avail(dr) < 1)) {
            blk_stop_queue(port->disk->queue);
            err = -ENOMEM;
            goto out;
      }

      desc = vio_dring_cur(dr);

      err = ldc_map_sg(port->vio.lp, sg, nsg,
                   desc->cookies, port->ring_cookies,
                   map_perm);
      if (err < 0) {
            printk(KERN_ERR PFX "ldc_map_sg() failure, err=%d.\n", err);
            return err;
      }

      rqe = &port->rq_arr[dr->prod];
      rqe->req = req;

      desc->hdr.ack = VIO_ACK_ENABLE;
      desc->req_id = port->req_id;
      desc->operation = op;
      if (port->vdisk_type == VD_DISK_TYPE_DISK) {
            desc->slice = 0xff;
      } else {
            desc->slice = 0;
      }
      desc->status = ~0;
      desc->offset = (req->sector << 9) / port->vdisk_block_size;
      desc->size = len;
      desc->ncookies = err;

      /* This has to be a non-SMP write barrier because we are writing
       * to memory which is shared with the peer LDOM.
       */
      wmb();
      desc->hdr.state = VIO_DESC_READY;

      err = __vdc_tx_trigger(port);
      if (err < 0) {
            printk(KERN_ERR PFX "vdc_tx_trigger() failure, err=%d\n", err);
      } else {
            port->req_id++;
            dr->prod = (dr->prod + 1) & (VDC_TX_RING_SIZE - 1);
      }
out:

      return err;
}

static void do_vdc_request(struct request_queue *q)
{
      while (1) {
            struct request *req = elv_next_request(q);

            if (!req)
                  break;

            blkdev_dequeue_request(req);
            if (__send_request(req) < 0)
                  vdc_end_request(req, 0, req->hard_nr_sectors);
      }
}

static int generic_request(struct vdc_port *port, u8 op, void *buf, int len)
{
      struct vio_dring_state *dr;
      struct vio_completion comp;
      struct vio_disk_desc *desc;
      unsigned int map_perm;
      unsigned long flags;
      int op_len, err;
      void *req_buf;

      if (!(((u64)1 << ((u64)op - 1)) & port->operations))
            return -EOPNOTSUPP;

      switch (op) {
      case VD_OP_BREAD:
      case VD_OP_BWRITE:
      default:
            return -EINVAL;

      case VD_OP_FLUSH:
            op_len = 0;
            map_perm = 0;
            break;

      case VD_OP_GET_WCE:
            op_len = sizeof(u32);
            map_perm = LDC_MAP_W;
            break;

      case VD_OP_SET_WCE:
            op_len = sizeof(u32);
            map_perm = LDC_MAP_R;
            break;

      case VD_OP_GET_VTOC:
            op_len = sizeof(struct vio_disk_vtoc);
            map_perm = LDC_MAP_W;
            break;

      case VD_OP_SET_VTOC:
            op_len = sizeof(struct vio_disk_vtoc);
            map_perm = LDC_MAP_R;
            break;

      case VD_OP_GET_DISKGEOM:
            op_len = sizeof(struct vio_disk_geom);
            map_perm = LDC_MAP_W;
            break;

      case VD_OP_SET_DISKGEOM:
            op_len = sizeof(struct vio_disk_geom);
            map_perm = LDC_MAP_R;
            break;

      case VD_OP_SCSICMD:
            op_len = 16;
            map_perm = LDC_MAP_RW;
            break;

      case VD_OP_GET_DEVID:
            op_len = sizeof(struct vio_disk_devid);
            map_perm = LDC_MAP_W;
            break;

      case VD_OP_GET_EFI:
      case VD_OP_SET_EFI:
            return -EOPNOTSUPP;
            break;
      };

      map_perm |= LDC_MAP_SHADOW | LDC_MAP_DIRECT | LDC_MAP_IO;

      op_len = (op_len + 7) & ~7;
      req_buf = kzalloc(op_len, GFP_KERNEL);
      if (!req_buf)
            return -ENOMEM;

      if (len > op_len)
            len = op_len;

      if (map_perm & LDC_MAP_R)
            memcpy(req_buf, buf, len);

      spin_lock_irqsave(&port->vio.lock, flags);

      dr = &port->vio.drings[VIO_DRIVER_TX_RING];

      /* XXX If we want to use this code generically we have to
       * XXX handle TX ring exhaustion etc.
       */
      desc = vio_dring_cur(dr);

      err = ldc_map_single(port->vio.lp, req_buf, op_len,
                       desc->cookies, port->ring_cookies,
                       map_perm);
      if (err < 0) {
            spin_unlock_irqrestore(&port->vio.lock, flags);
            kfree(req_buf);
            return err;
      }

      init_completion(&comp.com);
      comp.waiting_for = WAITING_FOR_GEN_CMD;
      port->vio.cmp = &comp;

      desc->hdr.ack = VIO_ACK_ENABLE;
      desc->req_id = port->req_id;
      desc->operation = op;
      desc->slice = 0;
      desc->status = ~0;
      desc->offset = 0;
      desc->size = op_len;
      desc->ncookies = err;

      /* This has to be a non-SMP write barrier because we are writing
       * to memory which is shared with the peer LDOM.
       */
      wmb();
      desc->hdr.state = VIO_DESC_READY;

      err = __vdc_tx_trigger(port);
      if (err >= 0) {
            port->req_id++;
            dr->prod = (dr->prod + 1) & (VDC_TX_RING_SIZE - 1);
            spin_unlock_irqrestore(&port->vio.lock, flags);

            wait_for_completion(&comp.com);
            err = comp.err;
      } else {
            port->vio.cmp = NULL;
            spin_unlock_irqrestore(&port->vio.lock, flags);
      }

      if (map_perm & LDC_MAP_W)
            memcpy(buf, req_buf, len);

      kfree(req_buf);

      return err;
}

static int __devinit vdc_alloc_tx_ring(struct vdc_port *port)
{
      struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
      unsigned long len, entry_size;
      int ncookies;
      void *dring;

      entry_size = sizeof(struct vio_disk_desc) +
            (sizeof(struct ldc_trans_cookie) * port->ring_cookies);
      len = (VDC_TX_RING_SIZE * entry_size);

      ncookies = VIO_MAX_RING_COOKIES;
      dring = ldc_alloc_exp_dring(port->vio.lp, len,
                            dr->cookies, &ncookies,
                            (LDC_MAP_SHADOW |
                             LDC_MAP_DIRECT |
                             LDC_MAP_RW));
      if (IS_ERR(dring))
            return PTR_ERR(dring);

      dr->base = dring;
      dr->entry_size = entry_size;
      dr->num_entries = VDC_TX_RING_SIZE;
      dr->prod = dr->cons = 0;
      dr->pending = VDC_TX_RING_SIZE;
      dr->ncookies = ncookies;

      return 0;
}

static void vdc_free_tx_ring(struct vdc_port *port)
{
      struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];

      if (dr->base) {
            ldc_free_exp_dring(port->vio.lp, dr->base,
                           (dr->entry_size * dr->num_entries),
                           dr->cookies, dr->ncookies);
            dr->base = NULL;
            dr->entry_size = 0;
            dr->num_entries = 0;
            dr->pending = 0;
            dr->ncookies = 0;
      }
}

static int probe_disk(struct vdc_port *port)
{
      struct vio_completion comp;
      struct request_queue *q;
      struct gendisk *g;
      int err;

      init_completion(&comp.com);
      comp.err = 0;
      comp.waiting_for = WAITING_FOR_LINK_UP;
      port->vio.cmp = &comp;

      vio_port_up(&port->vio);

      wait_for_completion(&comp.com);
      if (comp.err)
            return comp.err;

      err = generic_request(port, VD_OP_GET_VTOC,
                        &port->label, sizeof(port->label));
      if (err < 0) {
            printk(KERN_ERR PFX "VD_OP_GET_VTOC returns error %d\n", err);
            return err;
      }

      err = generic_request(port, VD_OP_GET_DISKGEOM,
                        &port->geom, sizeof(port->geom));
      if (err < 0) {
            printk(KERN_ERR PFX "VD_OP_GET_DISKGEOM returns "
                   "error %d\n", err);
            return err;
      }

      port->vdisk_size = ((u64)port->geom.num_cyl *
                      (u64)port->geom.num_hd *
                      (u64)port->geom.num_sec);

      q = blk_init_queue(do_vdc_request, &port->vio.lock);
      if (!q) {
            printk(KERN_ERR PFX "%s: Could not allocate queue.\n",
                   port->vio.name);
            return -ENOMEM;
      }
      g = alloc_disk(1 << PARTITION_SHIFT);
      if (!g) {
            printk(KERN_ERR PFX "%s: Could not allocate gendisk.\n",
                   port->vio.name);
            blk_cleanup_queue(q);
            return -ENOMEM;
      }

      port->disk = g;

      blk_queue_max_hw_segments(q, port->ring_cookies);
      blk_queue_max_phys_segments(q, port->ring_cookies);
      blk_queue_max_sectors(q, port->max_xfer_size);
      g->major = vdc_major;
      g->first_minor = port->vio.vdev->dev_no << PARTITION_SHIFT;
      strcpy(g->disk_name, port->disk_name);

      g->fops = &vdc_fops;
      g->queue = q;
      g->private_data = port;
      g->driverfs_dev = &port->vio.vdev->dev;

      set_capacity(g, port->vdisk_size);

      printk(KERN_INFO PFX "%s: %u sectors (%u MB)\n",
             g->disk_name,
             port->vdisk_size, (port->vdisk_size >> (20 - 9)));

      add_disk(g);

      return 0;
}

static struct ldc_channel_config vdc_ldc_cfg = {
      .event            = vdc_event,
      .mtu        = 64,
      .mode       = LDC_MODE_UNRELIABLE,
};

static struct vio_driver_ops vdc_vio_ops = {
      .send_attr        = vdc_send_attr,
      .handle_attr            = vdc_handle_attr,
      .handshake_complete     = vdc_handshake_complete,
};

static void print_version(void)
{
      static int version_printed;

      if (version_printed++ == 0)
            printk(KERN_INFO "%s", version);
}

static int __devinit vdc_port_probe(struct vio_dev *vdev,
                            const struct vio_device_id *id)
{
      struct mdesc_handle *hp;
      struct vdc_port *port;
      int err;

      print_version();

      hp = mdesc_grab();

      err = -ENODEV;
      if ((vdev->dev_no << PARTITION_SHIFT) & ~(u64)MINORMASK) {
            printk(KERN_ERR PFX "Port id [%lu] too large.\n",
                   vdev->dev_no);
            goto err_out_release_mdesc;
      }

      port = kzalloc(sizeof(*port), GFP_KERNEL);
      err = -ENOMEM;
      if (!port) {
            printk(KERN_ERR PFX "Cannot allocate vdc_port.\n");
            goto err_out_release_mdesc;
      }

      if (vdev->dev_no >= 26)
            snprintf(port->disk_name, sizeof(port->disk_name),
                   VDCBLK_NAME "%c%c",
                   'a' + ((int)vdev->dev_no / 26) - 1,
                   'a' + ((int)vdev->dev_no % 26));
      else
            snprintf(port->disk_name, sizeof(port->disk_name),
                   VDCBLK_NAME "%c", 'a' + ((int)vdev->dev_no % 26));

      err = vio_driver_init(&port->vio, vdev, VDEV_DISK,
                        vdc_versions, ARRAY_SIZE(vdc_versions),
                        &vdc_vio_ops, port->disk_name);
      if (err)
            goto err_out_free_port;

      port->vdisk_block_size = 512;
      port->max_xfer_size = ((128 * 1024) / port->vdisk_block_size);
      port->ring_cookies = ((port->max_xfer_size *
                         port->vdisk_block_size) / PAGE_SIZE) + 2;

      err = vio_ldc_alloc(&port->vio, &vdc_ldc_cfg, port);
      if (err)
            goto err_out_free_port;

      err = vdc_alloc_tx_ring(port);
      if (err)
            goto err_out_free_ldc;

      err = probe_disk(port);
      if (err)
            goto err_out_free_tx_ring;

      dev_set_drvdata(&vdev->dev, port);

      mdesc_release(hp);

      return 0;

err_out_free_tx_ring:
      vdc_free_tx_ring(port);

err_out_free_ldc:
      vio_ldc_free(&port->vio);

err_out_free_port:
      kfree(port);

err_out_release_mdesc:
      mdesc_release(hp);
      return err;
}

static int vdc_port_remove(struct vio_dev *vdev)
{
      struct vdc_port *port = dev_get_drvdata(&vdev->dev);

      if (port) {
            del_timer_sync(&port->vio.timer);

            vdc_free_tx_ring(port);
            vio_ldc_free(&port->vio);

            dev_set_drvdata(&vdev->dev, NULL);

            kfree(port);
      }
      return 0;
}

static struct vio_device_id vdc_port_match[] = {
      {
            .type = "vdc-port",
      },
      {},
};
MODULE_DEVICE_TABLE(vio, vdc_port_match);

static struct vio_driver vdc_port_driver = {
      .id_table   = vdc_port_match,
      .probe            = vdc_port_probe,
      .remove           = vdc_port_remove,
      .driver           = {
            .name = "vdc_port",
            .owner      = THIS_MODULE,
      }
};

static int __init vdc_init(void)
{
      int err;

      err = register_blkdev(0, VDCBLK_NAME);
      if (err < 0)
            goto out_err;

      vdc_major = err;

      err = vio_register_driver(&vdc_port_driver);
      if (err)
            goto out_unregister_blkdev;

      return 0;

out_unregister_blkdev:
      unregister_blkdev(vdc_major, VDCBLK_NAME);
      vdc_major = 0;

out_err:
      return err;
}

static void __exit vdc_exit(void)
{
      vio_unregister_driver(&vdc_port_driver);
      unregister_blkdev(vdc_major, VDCBLK_NAME);
}

module_init(vdc_init);
module_exit(vdc_exit);

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